The Next (and Final) Doomsday Scenario

Personally, I love dystopian visions and apocalyptic nightmares. So, news that the famed Higgs boson may ultimately cause our demise, and incidentally the end of the entire cosmos, caught my attention.

Apparently theoreticians have calculated that the Higgs potential of which the Higgs boson is a manifestation has characteristics that make the universe unstable. (The Higgs was discovered in 2012 by teams at CERN’s Large Hadron Collider.) Luckily for those wishing to avoid the final catastrophe this instability may keep the universe intact for several more billions of years, and if suddenly the Higgs were to trigger the final apocalypse it would be at the speed of light.

From Popular Mechanics:

In July 2012, when scientists at CERN’s Large Hadron Collider culminated decades of work with their discovery of the Higgs boson, most physicists celebrated. Stephen Hawking did not. The famed theorist expressed his disappointmentthat nothing more unusual was found, calling the discovery “a pity in a way.” But did he ever say the Higgs could destroy the universe?

That’s what many reports in the media said earlier this week, quoting a preface Hawking wrote to a book called Starmus. According to The Australian, the preface reads in part: “The Higgs potential has the worrisome feature that it might become metastable at energies above 100 [billion] gigaelectronvolts (GeV). This could mean that the universe could undergo catastrophic vacuum decay, with a bubble of the true vacuum expanding at the speed of light. This could happen at any time and we wouldn’t see it coming.”

What Hawking is talking about here is not the Higgs boson but what’s called the Higgs potential, which are “totally different concepts,” says Katie Mack, a theoretical astrophysicist at Melbourne University. The Higgs field permeates the entire universe, and the Higgs boson is an excitation of that field, just like an electron is an excitation of an electric field. In this analogy, the Higgs potential is like the voltage, determining the value of the field.

Once physicists began to close in on the mass of the Higgs boson, they were able to work out the Higgs potential. That value seemed to reveal that the universe exists in what’s known as a meta-stable vacuum state, or false vacuum, a state that’s stable for now but could slip into the “true” vacuum at any time. This is the catastrophic vacuum decay in Hawking’s warning, though he is not the first to posit the idea.

Is he right?

“There are a couple of really good reasons to think that’s not the end of the story,” Mack says. There are two ways for a meta-stable state to fall off into the true vacuum—one classical way, and one quantum way. The first would occur via a huge energy boost, the 100 billion GeVs Hawking mentions. But, Mack says, the universe already experienced such high energies during the period of inflation just after the big bang. Particles in cosmic rays from space also regularly collide with these kinds of high energies, and yet the vacuum hasn’t collapsed (otherwise, we wouldn’t be here).

“Imagine that somebody hands you a piece of paper and says, ‘This piece of paper has the potential to spontaneously combust,’ and so you might be worried,” Mack says. “But then they tell you 20 years ago it was in a furnace.” If it didn’t combust in the furnace, it’s not likely to combust sitting in your hand.

Of course, there’s always the quantum world to consider, and that’s where things always get weirder. In the quantum world, where the smallest of particles interact, it’s possible for a particle on one side of a barrier to suddenly appear on the other side of the barrier without actually going through it, a phenomenon known as quantum tunneling. If our universe was in fact in a meta-stable state, it could quantum tunnel through the barrier to the vacuum on the other side with no warning, destroying everything in an instant. And while that is theoretically possible, predictions show that if it were to happen, it’s not likely for billions of billions of years. By then, the sun and Earth and you and I and Stephen Hawking will be a distant memory, so it’s probably not worth losing sleep over it.

What’s more likely, Mack says, is that there is some new physics not yet understood that makes our vacuum stable. Physicists know there are parts of the model missing; mysteries like quantum gravity and dark matter that still defy explanation. When two physicists published a paper documenting the Higgs potential conundrum in March, their conclusion was that an explanation lies beyond the Standard Model, not that the universe may collapse at any time.

Read the article here.